Peessing oe punching machine



Sept 11, 1928. 1,684,296

. G. BRODSKY PRESSING OR PUNCHING MACHINE Filed Dec. 16, 1925 2 Sheets-Sheet 1 G-rg ory Brodsky v W J? M Sept. 11, 1928.

(5.; BRODSKY PRESSING OR PUNCHING MACHINE Filed Dec. 16, 1925 2 Sheets-Sheet Patented Sept. 11, 1928.

UNITED STATES GREGORY BRODSKY, F WORCESTER, MASSACHUSETTS.

PRESSING OR PUNCHING MACHINE.

Application filed December 16, 1925.. Serial No. 75,855.

particularly characterized by the fact that the pressing or punching efiect is obtained as a result of electromagnetic forces acting on either one, or both of the members.

One object of my invention is to provide 1 an improved machine in which the energization of the members to exert pressure is always directly under the control of the operator, whereby the pressure on work, or any other object between the members, may be exerted or released, either automatically or manually at any desired stage in the operation of the machine.

Another object of my invention is to provide an improved pressing or punching machine in which the movable work performing member will be automatically arrested in its movement toward the work supporting memher and immediately withdrawn to an inoperative position should the moving member encounter an obstruction, such as a finger 'or hand, extraneous to the work supported between the members, whereby actual iniurv to the operator will be efleetively prevented. The above and other advantageous features of my invention will hereinafter more fully appear, with reference to the accompanying drawings. in which- Fig. 1 is a diagrammatic view illustrating the principle of my invention, the pressing members being shown in an inoperative posi tion.

Fig. 2 is a diagrammatic view similar to Fig. 1. showing the members in position for exerting pressure therebetween.

Fig. 3 is a diagrammatic view illustrating the functioning of my machine to prevent injury to an operator.

Fig. 4 is a view in front elevation of a box making machine embodying my invention.

Like reference characters refer to like parts in the diflerent figures.

Referring first to Figs. 1, 2 and 3, the principle of my invention will first be described with reference only to the essential elements of a pressing machine which generally comprises an anvil block 1 providing a recess 2 in which is yieldably supported an anvil, or work supporting die 3. vAn upper die, or work performing member 4 is carried by a plunger 5 supported for sliding movement in vertically spaced guides 6, 7 and 8. The plunger 5 is surroundedby a spring 9 between the lower guide 6 and a collar 10 carried by the plunger, whereby the pressing member 4 is maintained away from the work supporting die 3 a sufficient distance to permit the positioning of a piece of work between the dies 3 and i. The upper portion of the plunger 5 is surrounded by a solenoid 11 supported between the guides 7 and 8, and when the solenoid 11 is energized it will draw the plunger 5 downwardly to cause the pressing member 4. to engage the die 3, or the work supported thereon.

One terminal of the solenoid 11 is connected through a conductor 12 to a suitable source of electrical energy, indicated at 13, which source may be either direct or alternating current. The normal circuit of the conductor 12 includes a pivoted contact arm 14 main tained in engagement with a contact 15 by a spring 16 movable with the plunger 5. With this arrangement. one terminal of the solenoid 11 is connected to the source 13 practically all the time. the only break in this cireuit occurring when the pressing member 4 has reached the extreme lower end of its downward stroke, as will be hereinafter described. V

The other terminal of the solenoid 11 is adapted to be connected to the source 13 by means of a treadle switch 17 conveniently located for foot operation. which switch is maintained open except when pressure is applied thereto. The circuit from the switch 17 to the solenoid. 11 is adapted to be comple ed by two different current paths. one of which is between spaced contact members 18 adapted to be connected by a bridging member 19 carried by the work supporting die 3. Th other current path from the switch 17 to the solenoid 11 includes a contact member 20 movable with the plunger 5 and a relatively stationary, though vieldable. contact. member 21, the arrangement of the circuit being such that current can be supplied to the solenoid 11 either through the contacts 18 and bridging member 19. or through contacts 20 and 21, in accordance with. the position occupied by the plunger 5.

Assuming the parts to occupy the position, shown in Fig. 1. it will be apparent that when the treadle switch 17 is closed, current will flow through the solenoid 11, as indicated he the. arrows. and the slim ver 5. with the 1 pressing member 4, will start to descend by reason of the energization of the solenoid 11. When the descending pressing member 4t engages the die 3, or the work supported there between, the die 3 will be depressed by reason of its yieldable support on a spring 22 within the recess 2 in theanvil block 1, and as the bridging member 19 is carried by the die 3, the pressure thereof causes the circuit from the switch 17 to the solenoid 11 to be broken between the contacts 18. This interruption of the circuit between the cont-acts 18 would cause deenergization of the solenoid 11 and permit the spring 9 to retractthe pressing member 4 were it not for the factthat just as the member 4 engages the die 3, or the work supported therebetween, the plunger-carried contact 20 engages the yieldable contact 21. This engagement of the contacts 20 and 21 maintains the circuit between the switch 17 and the solenoid 11, as indicated in dotted lines in'Fig. 2, so that the member 4: completes itsdownward stroke, and pressure is exerted between thedies 3 and 4 as the die 3 bottoms in the recess 2 in the block 1.

As thedie 3 and member 4 reach the p ressure exerting position shown in Fig. 2, the spring 16, movable with the plunger 5, swings to apoint below the pivot of the contact arm 14, thereby exerting a force which separates the arm 14 from the contact 15 and breaks the circuit of the solenoid at this point. The solenoid 11 being thus deenergized, the spring 9 immediately raises the pressing member 1 to the position shown in Fig. 1', whereupon the spring 16 acting on the "arm 1.4 reestablishes the circuit from one terminal of the solenoid 11. It will be obvious, however, that as the plunger 5 moves upwardly, the contacts 20 and 21 will be separated, while the bridging member 19 will reenga'g'e the contacts 18. Consequently the solenoid 11 is again adapted to be energized by closing the treadle switch 17, it being also apparent that the circuit of the solenoid 11 can be broken at any time by releasing the treadle switch 17. Furthermore, the automatic rais ing of the plunger 5, following the engagement of the dies 3 and 4, can be dispensed with by locking the contact arm 14 and the contact 15 together, as by means of alever 23, see Fig. 2, in which event release of the tread'le switch 17 causes the plunger 5 to be raised,

Referrin now to Fig. '3, there is illustrated the functioning of the machine when thedescending pressing member 4- engagesan object extraneousto thework supported on the anvil 3, such as thefinger or hand of an operator, Vhen the descending member 4: thus encounters an obstruction, the force of the descending member 41 is momentarily transmitted through the finger to the yieldable die 3, the immediate depression ofwhich causes the bridging member 19 to leave the contacts 18, thus tie-energizing the solenoid 11, lVhen 'thecircuit of the solenoid is thus broke-n, it is obvious that the plunger-carried contact 20 has not at that time engaged the c ta 2: ,-.s9 that the pring 9 immediately withdraws the pressing member 1 from. the die 3 without any appreciable pressure having been exerted on the finger. Upon the release of the die 3 by the finger of the operator, the

circuit between the contacts 18 is reestablished and themachine is again in a position. to perform' a pressing operation, as illustrated in Fig. 1. 7 From the above description of the functioning of the machine, particularly from the standpoint of safety, it is obvious that my invention may "be advantageously employed in connection with many different rinds of machines for performingpressing and punching operations. In so far as 1 am aware most pressing and punching machines, as heretofore constructed, have been operated from a mechanical source of ower, such as a rotating shaft, from which one of the relatively movable pressing members derives a reciprocatory movement. An inherent defect of all of such power driven machines, however, arises from'the fact that when the reciprocatory plunger or head is connected to the source of power, that member invariably makes one complete downward stroke toward the work before the operator has an opportunity to disconnect the machine from the source of power. In my improved machine, however, the reciprocatory plunger is adapted to be moved toward the work'only when the solenoid 11 is energized, and as previously pointed out, the energization of the solenoid may be interrupted at any time b' the operators release of the treadle switch 1 Furthermore, the energization of the solenoid 11 is adapted to be automatically interrupted, either immediately following pressure between the dies 3 and 4, or upon the engagement of the descending die 4 with an object extraneous to the work between the dies} For the above reasons, my improved machine'is believed to be much safer than any pressing or punching machines lieretofope constructed, in which the question of safety has always been complicated by the utilization of a positive and continuous source of power. In such prior machines, the source of power once connected to the head or plunger, imparts a positive movement thereto, irrespective of the subsequent operation of any auxiliary safety device designed to render l-ul the work performing member ineffective,

' Whereas in my improved machine, the mov- Ian reason of the fact that the energization of the solenoid 11 is always jointly under the manual control of the operator and the automatic control of both work performing members themselves that my machine can be operated with a maximum degree of safety. Furthermore, the amount and duration of the pressure exerted between the dies 3 and 4 can be controlled Within a wide range by adjusting the pull of the solenoid 11 and by altering the relation between the various contacts in the control circuits thereof.

Referring now to Fig. 4;, my invention is shown embodied in a machine for attaching stay strips to the corners of boxes, the machine providing a suitable table or base 24, upon which is mounted a longitudinally adjustable anvil block 25 carrying ayieldably supported die 26 which is angular in form to support the corner of a box. A plunger 5 corresponding in all respects to the plunger shown in Fig. 1, is slidably supported on guides 6, 7 and 8 provided by an upward extension 27 of the base 24, and is adapted to be operated by a solenoid 11 controlled as in Fig. 1. The lower end of the plunger 5 carries a die 28 having a recess corresponding in form to the stationary die 26, it being evident that ressure between the dies 26 and 28 is adapte to attach a stay strip to a. corner of a box supported on the lower die 26. Staying machines employing cooperating dies of the form illustrated are in common use, and it is obvious that any suitable means may be employed for inserting the stay strips between the dies, such as is shown, for example, in my copending application Serial No. 91,544, filed March 1, 1926.

In the operation of a corner staying machine it is necessary for the operator to hold the corners ofthe box together on opposite sides of the apex of the lower die 26, and it frequently happens that one or more fingers are accidentally left within the path of the descending die 28. When a finger is left in this position,the depression of the die 26 and de energization of the solenoid 11 occurs almost simultaneousl with the engagement of the finger by the (lie 28, so thatno crushing of the finger results. It is also evident that should the operator depress'the die 26 by his fingers before closing the treadle switch 17, the machine will not function until the operator shifts his fingers out of the danger zone, thereby releasing the die 3.

When, however, the path below the de scending die 28 is free, the depression of the die 26 will not occur until the pressing die 28 has actually engaged the box, at which time, of course, it will be absolutely impossible for the operator to get even a portion of a finger between the engaged dies. In other words, the change over from the drawingdown circuit, indicated by arrows in Fig. 1, to the pressing circuit, indicated by arrows in Fig. 2, does not occur until after the pressing member 4 has actually engaged the work.

It is obvious that my invention may be incorporated in many other types of pressing and punching machines, in addition to corner stayers, without in any way departing from the principles underlying my invention. Furthermore, the circuit arrangements for controlling the energization of the plunger are susceptible of modification while still retaining the operating characteristics of the machine.

I claim:

1. In a machine of the class described, a safety device comprising relatively movable members, one of which is yieldable with respect to the other, an electromagnet for causing one of said members to approach the other, means for energizing said magnet to cause the approach of said members, means for automatically deenergizing said magnet upon the depression of the yieldable member, and means for automatically reenergizing said magnet when said members reach a predetermined relative position.

2. In a machine of the class described, a safety device comprising relatively movable members, one of which is yieldable with respect tothe other, an electromagnet for causing one of said members to approach the other, means for energizing said magnet to cause the approach of said'members, means for automatically deenergizing said magnet upon the depression of the yieldable member, and means controlled by the other member for automatically reenergizing said magnet when said members reach a predetermined relative position.

3. In a machine of the class described, a safet device comprising relatively movable mem ers, one of which is yieldable with respect to the other, an electromagnet for causing one of said members to approach the other, means for energizing said magnet to cause the approach of said members, means for automatically deenergizin said magnet upon the depression of the yieldable member, and means controlled by the moving member for automatically reenergizing said magnet when said members reach a predetermined relative position.

4:. In a machine of the class described, the combination with a pair of relatively movable members, and electromagnetic means to bring said members together, of a pair of electrical circuits to cause energization of said electromagnetic means, a switch under the control of an operator to close one of said circuits and thereby cause the approach of said members, automatic means operated by the said approach of the members to open the. operator controlled circuit, and automatic means to close the other of said circuits.

5. In a machine of the class described, the

combination with impair of relatively movable hers to close the other of said circuits, where members, and electromagnetic means to bring by said membersare brought together to per-- said members together, of a pair of electrical .form work when obstructed, but can-not be circuits to cause energization of said e1ectrobrought together if the movement of the magnetic means, a switch :under'the controiof member that controls the last named circuit an operator to close one of said circuits, :1 is obstructed because of the failure to com" M switch controlled by one of said members to I .plete the said last named circuit.

open said last named circuit, and another 7 I switch controlled by the other of said mem- GREGORY BRODSKY. 

